This invention relates to a pyrochemical process for converting spent oxide nuclear fuel from a light water reactor to metal and for separating plutonium and higher actinide metals such as americium, neptium and curium from the bulk uranium. Because the end product is for use in a integrated fast reactor (IFR), high decontamination of the separate streams from fission products is not a prime concern nor is the total separation of plutonium americium, neptunium and curium (hereinafter transuranic elements) from the bulk uranium. The transuranic or transuranium elements will be used to make core fuel for a liquid metal fast breeder (LMFBR) particularly of the new IFR or integrated fast reactor type. Because of the purpose for which this reprocessed fuel will be used, some uranium can accompany the plutonium stream since the uranium to plutonium ratio in a LMFBR fuel is in the range of 2-3.5:1. The bulk uranium or uranium rich product stream is to be stored for later use, for instance as a uranium source for breeder blankets in a liquid metal fast breeder reactor (LMFBR), when and if such fast reactors are commercially viable. A goal of the process is to remove more than 90% of the transuranic or transuranium actinides from the uranium so that the transuranic actinides can be used as core fuel and the remaining uranium can be used as blanket material.
Accordingly, it is an object of the invention to provide a process for separating transuranic or transuranium actinide values from spent oxide nuclear fuel while reducing the amount of nuclear waste material which has to be treated and stored.
Another object of the invention is to provide a process using various combinations of alloys, salts and liquid magnesium selectively to separate uranium from the transuranic values present in spent nuclear oxide fuel and to reuse the salts and the magnesium many times in order efficiently to separate the desired values while producing a very small amount of nuclear waste.
A still further object of the invention is to provide a process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products, comprising reducing the oxide fuel with Ca metal in the presence of Ca halide and a U-Fe alloy which is liquid at about 800.degree. C. to dissolve uranium metal and the noble metal fission products and transuranium actinide metals and rare earth fission product metals leaving Ca halide having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein, separating the Ca halide and CaO and the fission products contained therein from the U-Fe alloy and the metal values dissolved therein, contacting the U-Fe alloy having dissolved therein reduced metals from the spent nuclear fuel with a mixture of one or more halides selected from the class consisting of alkali metal or alkaline earth metal and Fe or U halide or a combination thereof to transfer transuranium actinide metals and rare earth metals to the halide salt leaving the uranium and noble metal fission products in the U-Fe alloy, and thereafter separating the halide salt and the transuranium metals dissolved therein from the U-Fe alloy and the metals dissolved therein.
Yet another object of this invention is to recontact the Fe and/or U chloride salt with the U-Fe alloy until not less than about 99% by weight of the transuranium actinides transfer to the chloride salt.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.